Exergoeconomic analysis of hydrogen production from biomass gasification

Abstract

In this study we investigate biomass-based hydrogen production through exergy and exergoeconomic analyses and evaluate all components and associated streams using an exergy cost energy and mass (EXCEM) method. Then we define the hydrogen unit cost and examine how key system parameters affect the unit hydrogen cost. Also we present a case study of the gasification process with a circulating fluidized bed gasifier (CFBG) for hydrogen production using the actual data taken from the literature. We first calculate energy and exergy values of all streams associated with the system exergy efficiencies of all equipment and determine the costs of equipment along with their thermodynamic loss rates and ratio of thermodynamic loss rate to capital cost. Furthermore we evaluate the main system components consisting of gasifier and PSA from the exergoeconomic point of view. Moreover we investigate the effects of various parameters on unit hydrogen cost such as unit biomass and unit power costs and hydrogen content of the syngas before PSA equipment and PSA hydrogen recovery. The results show that the CFBG system which has energy and exergy efficiencies of 55.11% and 35.74% respectively generates unit hydrogen costs between 5.37 $/kg and 1.59 $/kg according to the internal and external parameters considered. Copyright (C) 2012 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.